Radiation therapy after a partial response to CHOP chemotherapy for aggressive lymphomas

Purpose: To analyze the results with involved-field radiotherapy after aggressive lymphomas had decreased in size by 50-99% in response to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based chemotherapy. Methods and Materials: From 1988 through 1996, 294 previously untreated patients with Working Formulation intermediate-grade or large-cell immunoblastic lymphomas underwent CHOP-based chemotherapy on 2 consecutive protocols at the M. D. Anderson Cancer Center. Forty-four (15%) of these patients achieved, based on international working group guidelines, a partial (50-75%) response (n = 25), or unconfirmed complete (76-99%) response (n = 19) to a median of 6 cycles of chemotherapy. These patients were treated with salvage involved-field radiotherapy (n = 32) or chemotherapy (n = 12), e.g., MINE-ESHAP, without autologous stem-cell rescue (ASCR). Results: Median follow-up was 43 months. Partial responders experienced similar outcomes to unconfirmed complete responders. Local control (4-year rates: 86% vs. 53%, p = 0.009) and progression-free survival (4-year rates: 67% vs. 8%, p < 0.0001), but not overall survival (4-year rates: 70% vs. 50%, p = 0.067) were significantly better in those who received salvage radiotherapy, which was well tolerated. Conclusion: Progression-free and overall survival in aggressive lymphoma patients who underwent salvage radiotherapy were similar to results reported for high-dose chemotherapy with ASCR. The role of salvage radiotherapy in partial and unconfirmed complete responders to CHOP chemotherapy justifies examination in a large, cooperative group trial.